The International Journal of Oral & Maxillofacial Implants, 06/2013

Purpose: The aim of this pig model study was to verify whether the use of devices (surgical templates) or procedures (flapless or flap) of guided surgery may cause a potentially pathologic increase of temperature during the bone preparation. Materials and Methods: In this in vitro study, pig ribs with mean cortical thickness of 1.90 mm were used. Open-flap and flapless guided surgery (experimental groups OGS and FGS) and openflap and flapless conventional technique (control groups OSS and OFS) were performed. Temperature changes were recorded at a distance of 0.5 mm from the final test osteotomy by 2 thermocouples at depths of 1.5 (point A) and 12 mm (point B). Data were collected from 80 measurements, 10 for each group. Results: A statistically significant increase of temperature was reported for the FGS and OGS groups considering the measurement at point A (mean Δt 4.81 degrees and 4.21 degrees, respectively). The measurement at Point B for the FGS group compared to the FSS group did not differ significantly for the 3-mm drill, nor did the OSS group with the 2-mm drill. Conclusions: Site preparation with surgical stents generated higher bone temperature than conventional drilling. However, this heat generation did not reach temperature levels dangerous for the bone.

Purpose: To evaluate the long-term clinical performance of prosthetic reconstructions on one-piece implants, with a focus on technical and biological complications. Materials and Methods: An electronic MEDLINE search complemented by a manual search was conducted to identify randomized and prospective controlled clinical trials on one-piece implants. Additional inclusion criteria were a mean follow-up period of at least 5 years and an inception cohort where more than 80% of the enrolled patients remained in the study at the 5- or 10-year observation point. Results: Sixty-six studies from an initial yield of 597 titles were selected, and the data were extracted. Of the full-text articles examined, 46 were excluded and a total of 20 articles were finally selected. All studies were published between 1995 and 2011. Two different study designs were identified: 4 randomized controlled trials and 16 prospective cohort studies. The studies were analyzed and classified according to study type, patient characteristics, prosthetic characteristics, and biologic and technical complications after 5 and 10 years. The meta-analysis of the included studies showed a prosthetic survival rate for one-piece, one-part implants of 82.81% after 5 years and 97.85% and 98.24% in two-part implants after 5 and 10 years, respectively. Although the prosthetic survival rates were high, complications were frequent: complications of the suprastructure (18.44% to 18.75%), screw loosening/fracture (7.64%), soft-tissue complications (4.69% to 8.25%), sensory disturbances (0.36% to 6.25%), implant loss before loading (0% to 0.23%) and during function (1.10% to 3.21%), and implant fracture (0.0004%). Conclusion: Within the limits of this systematic review, it can be concluded that despite high long-term prosthetic survival rates, technical and biologic complications are frequent in one-piece implants, both in one-part and two-part designs. Further randomized clinical trials are needed to provide more information about the outcome of different variables associated with this type of implant design.

Purpose: This double-blind randomized controlled trial assessed the effect of subgingival ozone (O3, gaseous ozone, HealOzone MK II, KaVo) and/or hydrogen peroxide (H2O2) on the development of peri-implant mucositis. Materials and Methods: Twenty subjects (mean age, 60 ± 7.7 years) with 80 implants (4 implants each) were recruited. First, a 2-week pretrial phase took place to achieve healthy gingiva. Subsequently, partial gum shields were constructed for the experimental area (around the 4 implants); subjects were asked to refrain from brushing in that area by wearing the gum shield. The following treatments were randomly applied (for 60 seconds) to implant sites on days 0, 7, and 14: (1) air (O2) and saline (0.9% NaCl) (control group), (2) O2 and H2O2 (3%), (3) O3 and saline, and (4) O3 and H2O2. Plaque, gingival, and bleeding indices were recorded on days 0, 7, 14, and 21. Results: Significant differences were seen among the treatments (P .01) in plaque (F = 16.68), modified gingival (F = 7.86), and bleeding (F = 18.42) indices. O3 + saline and O3 + H2O2 produced optimum gingival health scores and were equally effective and the most effective in controlling bleeding (mean score = 0.05), while O2 + saline was the least effective (mean score = 0.56). Conclusion: Ozone showed great potential for management of peri-implant mucositis.

Purpose: This article describes the preliminary findings of the mechanical properties of functionally graded titanium with controlled distribution of porosity and a reduced Young's modulus on the basis of a computeraided design (CAD) file, using the rapid-prototyping, direct metal laser sintering (DMLS) technique. Materials and Methods: Sixty specimens of Ti-6Al-4V were created using a DMLS machine (M270) following the standard for tensile testing of metals. One group was fabricated with only 170 W of laser energy to create fully dense specimens (control group). The remaining specimens all featured an outer fully dense "skin" layer and a partially sintered porous inner "core" region. The outer "skin" of each specimen was scanned at 170 W and set at a thickness of 0.35, 1.00, or 1.50 mm for different specimen groups. The inner "core" of each specimen was scanned at a lower laser power (43 or 85 W). Results: The partially sintered core was clearly visible in all specimens, with somewhat greater porosity with the lower laser power. However, the amount of porosity in the core region was not related to the laser power alone; thinner skin layers resulted in higher porosity for the same power values in the core structure. The lowest Young's modulus achieved, 35 GPa, is close to that of bone and was achieved with a laser power of 43 W and a skin thickness of 0.35 mm, producing a core that comprised 74% of the total volume. Conclusion: Additive manufacturing technology may provide an efficient alternative way to fabricate customized dental implants based on a CAD file with a functionally graded structure that may minimize stress shielding and improve the long-term performance of dental implants.

Purpose: This study was conducted to evaluate the effectiveness of natural antimicrobial agents in reducing biofilm development on different titanium and zirconia dental implant materials in vitro using a constant depth film fermentor (CDFF). Materials and Methods: Contact angles and surface free energy were determined for all surfaces. Biofilms were grown on disks of polished partially stabilized zirconia, titanium blasted with zirconia, titanium blasted with zirconia and acid-etched, and polished titanium using a CDFF to simulate oral cavity conditions. Antimicrobials (cinnamon oil, clove oil, chlorhexidine gluconate, or 0.5% Tween 80) were pulsed twice daily to the biofilm to mimic application in the oral cavity. Samples were taken after 6, 24, and 48 hours. Serial dilutions were made and plated onto agar. Bacterial colonies were counted to determine colony-forming units/mL. Results: Treatment of different implant material surfaces with the various antimicrobial agents led to significant increases in wettability and free energy on all surfaces. All surfaces showed a remarkable decrease in bacterial adhesion in the first 2 days in a relatively similar manner, with significant reduction in most of them, particularly after 48 hours. Conclusions: Functionalization of different dental implant material surfaces with essential oils resulted in immediate and ongoing antibacterial and antiplaque activities, and this antibacterial effect was enhanced with increased plaque age. Differences in the type of material seemed to have little effect on bacterial adhesion after treatment with antimicrobial agents. Expansion of this work with in vivo studies and clinical trials would be valuable.

Purpose: This study compared osseointegration of implants placed 14 days after implant site preparation with that of immediately placed implants in rabbit femurs. Materials and Methods: Implants were placed bilaterally in the femoral condyles of 12 rabbits. On one side, the implants were placed 14 days after osteotomy, and the other side received implants immediately after osteotomy. Healing was assessed by microcomputed tomography and histomorphometry. Results: The delayed implants (placed 14 days after osteotomy) showed better osseointegration than the immediately placed implants. Bone-to-implant contact and bone volume, as assessed by histomorphometry and microcomputed tomography, were significantly higher for the implants placed after 14 days. Conclusions: From this study, it can be concluded that early osteotomy bed preparation and placement of implants after a 2-week delay predisposes to better boneimplant interface healing.

Purpose: This in vitro study evaluated the accuracy of multiple-unit dental implant casts obtained from splinted or nonsplinted direct impression techniques using various splinting materials by comparing the casts to the reference models. The effect of two different impression materials on the accuracy of the implant casts was also evaluated for abutment-level impressions. Materials and Methods: A reference model with six internal-connection implant replicas placed in the completely edentulous mandibular arch and connected to multi-base abutments was fabricated from heat-curing acrylic resin. Forty impressions of the reference model were made, 20 each with polyether (PE) and polyvinylsiloxane (PVS) impression materials using the open tray technique. The PE and PVS groups were further subdivided into four subgroups of five each on the bases of splinting type: no splinting, bite registration PE, bite registration addition silicone, or autopolymerizing acrylic resin. The positional accuracy of the implant replica heads was measured on the poured casts using a coordinate measuring machine to assess linear differences in interimplant distances in all three axes. The collected data (linear and three-dimensional [3D] displacement values) were compared with the measurements calculated on the reference resin model and analyzed with nonparametric tests (Kruskal-Wallis and Mann-Whitney). Results: No significant differences were found between the various splinting groups for both PE and PVS impression materials in terms of linear and 3D distortions. However, small but significant differences were found between the two impression materials (PVS, 91 μm; PE, 103 μm) in terms of 3D discrepancies, irrespective of the splinting technique employed. Conclusions: Casts obtained from both impression materials exhibited differences from the reference model. The impression material influenced impression inaccuracy more than the splinting material for multiple-unit abutment-level impressions.

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

Purpose: Implantoplasty, a procedure that is done to smooth contaminated implant surfaces, has been used in the treatment of peri-implantitis. It reduces the implant diameter, which might compromise the implant's strength. This in vitro study was designed to evaluate the effect of implantoplasty on implant strength. Materials and Methods: Thirty-two tapered implants were used; half were 3.75 mm in diameter (narrow) and the other half were 4.7 mm in diameter (wide). All implants were connected to 20-degree angled abutments. The apical half of each implant was embedded in acrylic resin. Eight 3.75-mm- and eight 4.7-mm-diameter implants were randomly assigned to receive implantoplasty. The remaining implants did not receive implantoplasty (control group). Implantoplasty was performed with a series of diamond and polishing burs. The specimens were then loaded 30 degrees off-axis in a universal testing machine until fracture failure occurred. Bending and fracture strength values were recorded and analyzed statistically (α = .05). The fractured surfaces were evaluated under a scanning electron microscope. Results: All narrow implants failed by fracture at the implant platform. The mean bending strength of narrow implants was statistically significantly reduced by implantoplasty (511.4 ± 55.9 N versus 613.9 ± 42.8 N). Implantoplasty did not affect the strength of wide implants; fracture failures occurred at the abutment screw. The fracture mode was ductile and the crack growth was oblique in direction, indicating complex stress distribution and concentration under loading. Conclusion: Within the limits of this study, implantoplasty appeared to weaken the strength of narrower implants. Therefore, this procedure should be performed with caution on narrower, freestanding implants that are subject to greater occlusal force (eg, posterior regions). Validation of these results is needed for different implant systems.

Purpose: The aim of this systematic review was to investigate the effect of keratinized mucosa width (KMW) on clinical parameters of peri-implant health and stability. Materials and Methods: Two independent reviewers conducted a comprehensive search to identify studies on human subjects reporting KMW as a bivariate factor (≥ 2 mm and 2 mm), along with mean pocket depth (PD), bleeding on probing (BOP), modified Bleeding Index (mBI), Gingival Index (GI), Plaque Index (PI), modified PI (mPI), and implant survival with a minimum follow-up of 6 months after implant loading. Eight studies were included in the systematic review and seven in the metaanalyses to ascertain summary effects for differences in the aforementioned parameters among groups of KMW. Results: Pooled analyses showed that GI, PI, and mPI were significantly higher in the group with KMW of 2 mm, while mBI was also higher but only marginally significant. In contrast, PD was not significantly different between the two groups. Differences in BOP and implant survival rate could not be analyzed because of limited data availability. Heterogeneity was highly significant among the pooled studies for all investigated variables. Conclusion: Reduced KMW around implants appears to be associated with clinical parameters indicative of inflammation and poor oral hygiene. However, based on the selected evidence, the predictive value of KMW is limited.

Purpose: This human study sought to compare, from an immunohistochemical point of view, matrix metalloproteinases (MMPs) 2, 3, 8, 9, and 13 in the soft tissues around titanium and zirconium oxide healing caps. Materials and Methods: Five patients participated in this study. All patients received 3.8 × 11-mm dental implants, which were left to heal in a nonsubmerged (single-stage) mode. Healing caps (3.8 mm in diameter and 3.0 mm in height) were inserted in all implants. Half of the implants were randomly supplied with standard, prefabricated caps of commercially pure titanium (control), while the other half were randomly provided with zirconium oxide caps (test). After a 6-month healing period, gingival biopsy specimens were obtained with a circular scalpel around the healing caps of both groups, without unscrewing or removing the healing caps, and the samples underwent immunohistochemical processing for MMPs 2, 3, 8, 9, and 13. Results: Statistically significant differences were found in the values of MMP-8 in the cells of the inflammatory infiltrate, with higher values for the titanium samples. Statistically significantly higher values were found, also in the titanium samples, for MMP-9 in the endothelial cells of the blood vessels. No statistically significant differences were found for any other MMPs. Conclusions: The present results showed that the soft tissues around titanium healing caps underwent a higher rate of restorative processes, most probably correlated to the MMP levels observed in the tissues.

Purpose: This study sought to prospectively evaluate changes in marginal bone levels and soft tissue dimensions around platform-switched, Morse taper-connection implants placed with the implant-abutment interface (IAI) at different positions in relation to the alveolar crest. Materials and Methods: Thirty patients in need of single-tooth rehabilitations were randomly assigned to three groups based on the position of the IAI in relation to the alveolar crest at the time of implant placement. Implants in groups 0, 1, and 2 (n = 10 in each group) were placed at the bone level or 1 mm and 2 mm below the buccal aspect of the alveolar crest, respectively. Four months later, the implants were restored with crowns. Clinical parameters were recorded at 4 and 12 months, and marginal bone levels were assessed radiographically at placement, 4 months, and 12 months. Results: Mean marginal bone loss below the implant platform in group 0 implants was 0.18 ± 0.27 mm at 4 months and 0.27 ± 0.45 mm at 12 months. All implants in groups 1 and 2 exhibited no marginal bone loss below the implant platform, since the first bone-to-implant contact was located at or above the implant margin. At 12 months, implants in groups 1 and 2 exhibited greater mean bone loss above the implant platform compared to implants in group 0, but the differences were not statistically significant (group 0, 0.64 ± 0.49 mm; group 1, 0.81 ± 0.31 mm; group 2, 1.20 ± 0.68 mm). Implants in groups 1 and 2 exhibited a statistically significantly higher percentage of implant surfaces with bone on the implant platform compared to group 0 implants (90% versus 35%). Conclusions: In the present study, differences in peri-implant bone responses existed for implants placed with the IAI at different locations in relation to the alveolar crest.

Purpose: To assess the clinical and tomographic findings of a grafting approach without barrier membranes to treat peri-implant buccal bone dehiscences at the time of implant placement. Materials and Methods: This retrospective study was conducted on all patients who needed implant placement with buccal bone grafting and were treated consecutively between March 2007 and June 2010. Two different implant systems were used (PSI, Globtek; XiVE Plus, Dentsply/Friadent). All sites had thick soft tissue (> 2 mm). All bone dehiscences were completely grafted with biphasic calcium phosphate and covered only by a soft tissue flap. Cone beam computed tomographic images were used to assess vertical buccal bone loss by measuring the distance between the implant platform and the first buccal bone contact with the implant body. Statistical analysis (Mann-Whitney test) was carried out to compare the outcomes from the two different implant systems analyzed. Results: Forty-one subjects (18 men, 23 women; mean age 57.3 ± 10.4 years) were selected and received 60 implants (52 delayed and 8 immediate placement). Mean follow-up was 26 months (range, 18 to 39 months). All 8 immediate implants and 33 of the 52 delayed implants presented buccal bone loss from 0 to 0.5 mm. Only two delayed sites presented buccal bone loss over 2 mm. No significant differences were seen between the implant systems. The study implant cumulative success rate was 100% (mean follow-up, 26 months). Conclusion: Predictable outcomes can be obtained by grafting buccal bone dehiscence areas without barrier membranes in sites with a minimum soft tissue thickness greater than 2 mm.

Purpose: Extended grafting procedures in atrophic ridges are invasive and time-consuming and increase cost and patient morbidity. Therefore, ridge-splitting techniques have been suggested to enlarge alveolar crests. The aim of this cohort study was to report techniques and radiographic outcomes of implants placed simultaneously with a piezoelectric alveolar ridge-splitting technique (RST). Peri-implant bone-level changes (ΔIBL) of implants placed with (study group, SG) or without RST (control group, CG) were compared. Materials and Methods: Two cohorts (seven patients in each) were matched regarding implant type, position, and number; superstructure type; age; and gender and received 17 implants each. Crestal implant bone level (IBL) was measured at surgery (T0), loading (T1), and 1 year (T2) and 2 years after loading (T3). For all implants, ΔIBL values were determined from radiographs. Differences in ΔIBL between SG and CG were analyzed statistically (Mann-Whitney U test). Bone width was assessed intraoperatively, and vertical bone mapping was performed at T0, T1, and T3. Results: After a mean observation period of 27.4 months after surgery, the implant survival rate was 100%. Mean ΔIBL was -1.68 ± 0.90 mm for SG and -1.04 ± 0.78 mm for CG (P = .022). Increased ΔIBL in SG versus CG occurred mainly until T2. Between T2 and T3, ΔIBL was limited (-0.11 ± 1.20 mm for SG and -0.05 ± 0.16 mm for CG; P = .546). Median bone width increased intraoperatively by 4.7 mm. Conclusions: Within the limitations of this study, it can be suggested that RST is a well-functioning one-stage alternative to extended grafting procedures if the ridge shows adequate height. ΔIBL values indicated that implants with RST may fulfill accepted implant success criteria. However, during healing and the first year of loading, increased IBL alterations must be anticipated.

Purpose: It has been hypothesized that a correlation exists between the density of surrounding cortical bone and the stability of an implant under percussion loading that can be used to quantify the implant's osseointegration. The purpose of the present research was to explore whether quantitative percussion testing of dental implants gives reasonable indications of the level of osseointegration that are consistent with bone configuration and its influence on osseointegration quality. Materials and Methods: Data from percussion testing of a live human subject, obtained using the Periometer, were compared with corresponding bone density estimates from high-resolution computed tomography images and postmortem percussion probe data. Results: The results confirm the hypothesis that the nature of an implant's response to percussion is determined by its cortical bone support. Conclusions: The findings suggest that the cortical bone supporting the crestal and apical regions of the implant is primarily responsible for structural stability.

Purpose: Ultraviolet (UV) light treatment of titanium, or photofunctionalization, has been shown to enhance its osteoconductivity in animal and in vitro studies, but its clinical performance has yet to be reported. This clinical case series sought to examine the effect of photofunctionalization on implant success, healing time, osseointegration speed, and peri-implant marginal bone level changes at 1 year after restoration. Materials and Methods: Four partially edentulous patients were included in the study. Seven implants with identical microroughened surfaces were photofunctionalized with UV light for 15 minutes. Osseointegration speed was calculated by measuring the increase in implant stability quotient (ISQ) per month. Marginal bone levels were evaluated radiographically at crown placement and at 1 year. Results: All implants placed into fresh extraction sockets, vertically augmented bone, simultaneously augmented sinuses, or the site of a failing implant remained functional and healthy at 1 year, even with an earlier loading protocol (2.1 to 4.5 months). ISQs of 48 to 75 at implant placement had increased to 68 to 81 at loading. In particular, implants with low primary stability (initial ISQ 70) showed large increases in ISQ. The speed of osseointegration of photofunctionalized implants was considerably greater than that of as-received implants documented in the literature. Mean marginal bone levels were -0.35 ± 0.71 mm at crown placement and had significantly increased to 0.16 ± 0.53 mm at 1 year, with coronal gains in marginal bone level that surpassed the implant platform. No implants showed marginal bone loss. Conclusions: Within the limits of this study, photofunctionalization expedited and enhanced osseointegration of commercial dental implants in various clinically challenging/compromised bone conditions. Photofunctionalization resulted in preservation-and often a gain-of marginal bone level, and long-term large-scale clinical validation is warranted.

Purpose: The aim of this study was to compare clinical outcomes and stability following immediate loading of two types of tapered implants in the partially edentulous posterior maxilla and mandible. Materials and Methods: A randomized controlled trial with 1 year of follow-up was performed on participants missing two consecutive teeth in a posterior quadrant with tapered implants with a hybrid textured surface. Group 1 received Osstem TSIII HA implants, and group 2 received Zimmer TSV implants. Group 1 implants were 4.5 or 5.0 mm in diameter, and group 2 implants were 4.7 mm in diameter; all implants were 10 mm long. Subjects received provisional restorations within 48 hours. Definitive restorations were provided 3 months (mandible) or 6 months (maxilla) later. Outcome measures were survival and success rates, marginal bone level change, implant stability quotient, and peri-implant soft tissue indices. Results: Fifty participants completed the trial (group 1: 52 implants in 26 patients; group 2: 48 implants in 24 patients). The success rates were similar-98.1% in group 1 and 97.9% in group 2-at 12 months after immediate loading, but marginal bone loss was significantly different according to the implant design. Implant stability increased significantly in both arches. There were no significant differences in soft tissue indices between implant systems. Conclusion: If high primary stability is acquired, tapered implants with hybrid textured surfaces are predictable for immediate loading in the posterior maxilla and mandible. In spite of the influence of implant design on marginal bone loss, all tapered implants showed successful clinical outcomes and stability in immediate loading.

Purpose: The National Institute for Health and Welfare in Finland (THL) has maintained the Finnish Dental Implant Register since April 1994. The aim of this study was to use the Dental Implant Register to assess the influence of patient characteristics and background factors on dental implant removals in Finland from 1994 to 2012. Materials and Methods: THL granted permission to access the Finnish Dental lmplant Register (1994 to 2012) and assess the following factors: total implant placements, total implant removals, time from implant placement to removal, implant types, implant lengths, placed and failed implants by jaw and tooth type, and patient sex and age. Results: A total of 198,538 dental implants (51 different types) were placed between 1994 and 2012. A total of 3,318 (1.7%) of the placed implants were removed during the observation period. A total of 1,856 (1.8%) of the placed implants were removed from the maxilla and 1,462 (1.5%) from the mandible (P .001). A slight difference in the sex distribution concerning implant failures (3.1% in men vs 2.3% in women) was observed. The median removal time was 247 days postoperatively (range 0 to 11,383 days), and one-third of the implants were removed within the first 142 days. Most of the placed implants were 10 mm or longer (93.3%) with 12 mm being the most commonly used length (23.9%). Shorter implants (8 mm or less) were removed more often (2.5% removal rate) than 9 mm or longer implants (1.5% removal rate). The IMZ Implant system demonstrated the highest overall removal rates (8.5%), while Brånemark Nobel Direct (0.6%) demonstrated the lowest removal rates. Of the most commonly placed implant types (together comprising 60.9% of all implants placed), the Straumann (1.2%) and the Astra Implant (1.2%) systems demonstrated equally low removal rates. Conclusions: The overall dental implant removal rates in Finland are low. Only slight differences in gender and implant position were observed.

Purpose: The purpose of this investigation was to evaluate the effects of number and distribution of implants upon in vitro dislodging forces to a simulated implant-supported overdenture and to examine differences between several different attachment systems. Materials and Methods: An experiment was undertaken utilizing a model simulating a mandibular edentulous ridge with dental implants in positions on the model approximating tooth positions in the natural dentition. A cobalt-chromium-cast testing framework was used to measure the peak load required to disconnect an attachment. Four different types of commercially available attachments were used in various positions on the model in sequence to evaluate the effects of retention and stability of overdentures based on implant number and distribution: (1) ERA, (2) O-Ring, (3) Locator, and (4) Ball. For each group, 10 measurements were made of peak dislodging forces. Means were calculated and differences among the systems, directions, and groups were identified using a repeated measured analysis of variance (α = .05). Results: The interactions between the attachment system, direction of force, and implant number and distribution were statistically significant. Vertical dislodging forces of the simulated overdenture prosthesis increased with additional widely spaced implants. Oblique dislodging forces of the simulated prosthesis increased with additional widely spaced implants except in the two-implant model with all attachments, and in the four-implant groups with Locator attachments. Anteroposterior dislodging forces of a simulated overdenture prosthesis increased with additional widely spaced implants except in the four-implant groups with Ball and Locator attachments. Ball attachments reported the highest levels of retention and stability followed by Locator, O-Ring, and ERA. Conclusions: Within the limitations of this study, retention and stability of an implant overdenture prosthesis are significantly affected by implant number, implant distribution, and abutment type.

Purpose: To analyze and compare bone apposition at the interface of commercially available rough-surfaced, threaded implants with porous-surfaced, cylindrical implants after several healing periods in a rabbit model. In addition, the study aimed to elucidate the influence of the implant surface configuration on Streptococcus mutans adherence. Materials and Methods: Using a powder metallurgy technique, a new method was developed to produce titanium implants with a dense core and porous surface to increase bone-implant contact (BIC). Sixty implants were placed in 15 rabbits. In each rabbit, two experimental and two control implants were placed in the right or left tibia. The experimental implants were inserted under pressure into the surgical cavity, while the control implants were self-threaded. The rabbits were euthanized at 4, 8, and 12 weeks postinsertion for undecalcified histologic processing and morphometric evaluation of BIC. Additionally, 16 implants, eight experimental and eight control, were incubated with S mutans to evaluate adherence for each type of implant. Analysis of variance with repeated measures and the Student t test were applied, respectively. Results: Histology showed intimate bone-implant interfaces without soft tissue intervention in both groups. Poroussurfaced cylindrical implants showed a higher BIC (72.41% ± 9.47%) than the rough-surfaced screw implants (61.23% ± 14.12%) (P = .013), while no significant difference in S mutans adherence occurred (P = .351). The implant type effect was more pronounced in the 4-week healing period groups (P = .029). The percentage of BIC was similar throughout the healing periods (P = .333), but gradually increased over time. Conclusion: Within the limitations of this study, the results suggest that the new implant design increased BIC without provoking greater S mutans adherence.

Purpose: No clinical evidence-based data on a possible negative influence of osteopenia and harmful lifestyles on implant osseointegration have been published to date. However, chronic alcohol abuse has been related to a progressive osteoporotic state. The continuous effort on developing better performing surfaces might offer improvement in osseointegration rates in conditions of poor bone quality. The aim of the present study was to investigate, in vitro, the behavior of osteoblasts obtained from rats exposed to ethanol vapor for 7 weeks and cultured on an innovative titanium surface achieved by a double anodic spark deposition. Materials and Methods: Ethanol-exposed and unexposed (control) osteoblasts were cultured on an anodic spark-deposited titanium surface and compared to those cultured on an acid-etched one. Cell proliferation and synthesis of alkaline phosphatase, osteocalcin, collagen I, transforming growth factor-β1, interleukin-6, and tumor necrosis factor-α were measured at 3, 7, and 14 days of culture. Results: When cultured on the anodic spark-deposited titanium surface, ethanol-exposed osteoblasts recovered proliferation impairment. Anodic spark-deposited titanium surfaces significantly improved both ethanol-exposed and unexposed osteoblast bioactivity, particularly with regard to alkaline phosphatase and transforming growth factor-β1. Moreover, interleukin-6 release for ethanol-exposed osteoblasts was significantly reduced by the anodic spark-deposited titanium surface. Conclusion: Proliferative and synthetic cell processes altered by ethanol contact were positively and partially restored by contact with the tested innovative surface.

Purpose: The objective of this study was to evaluate peri-implant bone formation and osseointegration at titanium implants coated with multiple layers of recombinant human bone morphogenetic protein-2 (rhBMP-2) cDNA placed into canine mandibles. Materials and Methods: The rhBMP-2 plasmid was assembled on sandblasted/dual-acid-etched pure titanium implant surfaces using layer-by-layer assembly. The rhBMP-2 plasmid-coated implants were placed into the edentulous posterior mandibles of 12 adult beagle dogs. Implants without the rhBMP-2 plasmid coating served as controls. Treatments were randomized between jaw quadrants, and four implants were placed in each mandibular quadrant. After 4, 8, and 12 weeks in situ, mandibles were retrieved and prepared for removal torque testing and histomorphometric evaluation. Results: Eight layers of rhBMP-2 plasmid were assembled onto the implant surfaces. Histomorphometric analysis showed that, after 4 and 8 weeks of healing, the intrathread bone area (BA) was slightly higher for test implants (54.21% and 59.56%) than for control implants (38.48% and 54.98%), respectively, but no statistically significant differences were seen at any time points. Mechanical tests showed that the mean removal torque values of the rhBMP-2 cDNA-coated implants were greater than those of the control implants after 8 weeks of healing (91 Ncm versus 61 Ncm; P = .31). Conclusion: Coating implants with multiple layers of an rhBMP-2 plasmid did not promote peri-implant bone formation and osseointegration in this model.

Purpose: Bone grafting materials and methods have been used to compensate anatomical limitations and improve ridge and sinus structure for implant placement. The objective of this study was to evaluate the osteopromotive property of allogenic demineralized dentin matrix (DDM) as a bone grafting material using micro-computed tomography and blood biomarkers. Materials and Methods: Two surgical bone defects were created on the skull of 30 female New Zealand White rabbits. Experimental defects in 24 rabbits were filled with allogenic DDM applying guided bone regeneration technique, while the control defects were covered by membrane without receiving the graft. In the remaining six rabbits, both defects were left empty and these rabbits served as control for blood biomarkers. The 24 experimental rabbits were sacrificed after 15, 30, 60, and 90 days (n = 6 at each time point). Blood samples were collected from all rabbits at the baseline, 48 hours postsurgery, and at each time point. Results: Bone thickness was significantly higher in the experimental group at all time points. Micro-computed tomography results showed increased bone mass and superior bone quality in the experimental group. At all time points except for 48 hours postsurgery, the white blood cell count was numerically higher in control rabbits compared to experimental rabbits, suggesting a lack of inflammation or infection due to allogenic DDM. Bone-specific alkaline phosphatase activities were lower in both experimental and control groups at all time points in comparison to baseline values, which is indicative of either a lower rate of bone formation or bone turnover. Conclusions: Within the limitations of this study, allogenic demineralized dentin matrix significantly increased bone mass and improved bone quality without causing an inflammatory reaction or infection.

Purpose: Accurate recording of implant locations is essential for precise passively fitting prostheses with proper support. This in vitro study evaluated the accuracy of impressions made of parallel and nonparallel implants with different lengths of impression coping connections. Materials and Methods: A reference model containing four internal-connection implant analogs (two at 0 degrees and two at 30 degrees in relation to the perpendicular line) was fabricated. Thirty medium-consistency silicon impressions of this model were made using the open-tray impression technique. Three groups of 10 specimens each were made with different impression coping connection lengths (2, 1.5, or 1 mm). Impressions were poured with type IV stone. The positional accuracy of the implant replica heads in the x-, y-, and z-axes was evaluated using a coordinate measuring machine, and measurements were compared with the obtained dimensions from the reference model. Data were analyzed with two-way analysis of variance (α = .05). Results: There was no significant difference in impression accuracy, regardless of the lengths of the impression connections. Additionally, there was no significant difference between the impression accuracy of inclined and straight implants, except in the y-axis (P = .006). Conclusions: Within the limitations of this study, the accuracy of implant impressions did not differ for different lengths of transfer coping connections of inclined and straight implants.

Purpose: This study compared the loosening torque of experimental conical-head abutment screws to that of conventional flat-head screws of implants with external-hex (EH) and internal tri-channel (IT) connections before and after mechanical loading. Materials and Methods: Forty-four implant/screw/abutment assemblies were divided into four groups: EH/flat-head screw (EH), IT/flat-head screw (IT), EH/conical-head screw (EHCS), and IT/conical-head screw (ITCS). Three assemblies from each group were analyzed in a stereoscopic magnifier and then returned to their respective groups. One assembly was removed from each group and transversely sectioned for optical microscopy analysis. Abutments were tightened at 32 Ncm of torque; after 10 minutes, loosening torque was measured. The same abutments were then retightened with 32 Ncm of torque; after 10 minutes, they were mechanically loaded for 300,000 cycles and loosening torque was again measured. Data were collected and an exploratory analysis was performed. Comparisons were made by orthogonal contrasts using a linear mixed effects model (random and fixed effects). Results: Comparisons before mechanical cycling showed significant differences between groups except for EH vs IT and EHCS vs ITCS. After mechanical cycling, only the comparisons EH vs IT and EHCS vs ITCS showed no significant differences. Considering the same group, before and after mechanical cycling, all comparisons showed significant differences. Conclusions: The shape of the abutment screw head significantly influenced loosening torque: conical-head screws showed higher loosening torque values than conventional flat-head screws before and after loading. The implant/abutment connection design exerted no significant influence on loosening torque.

This paper is a retrospective report of the treatment of six patients with severely resorbed maxillae. Patients were treated, based on the amount of maxillary retrognathia, with either a Le Fort I downfracture or a "horseshoe" interpositional sandwich osteotomy, along with sinus elevation. Recombinant human bone morphogenetic protein-2 in an absorbable collagen sponge carrier was used for grafting in all patients, either alone or in combination with other grafting materials. Implants were placed and the patients were restored with fixed prostheses. Both grafting techniques are described, and the treated patients are presented.

Purpose: To evaluate the use of a nonperforated titanium occlusive device over a bone morphogenetic protein-2 in an absorbable collagen sponge (BMP-2/ACS) in grafting the bone around high-profile (ie, supracrestal) dental implants in rabbit tibiae. Materials and Methods: Eight New Zealand white rabbits were used for the experiment. Two implants were placed in the right tibia of each rabbit, with 4 mm of each implant placed supracrestally ("high-profile" placement) in four groups of two rabbits each: control, titanium shell only, titanium shell over buffered collagen, and titanium shell over BMP-2/ACS. The animals were sacrificed after 3 or 6 weeks. Calcified and nondecalcified histologic preparation was carried out to evaluate bone formation and degree of osseointegration. Results: Three of the eight animals developed tibial fractures. The two BMP-2 test animal tibiae remained intact, with the 3-week specimen showing very little bone formation inside or outside of the titanium chamber and the 6-week specimen showing bone mostly outside of the chamber. Conclusion: The placement of BMP-2 beneath an occlusive nonperforated titanium shell next to a high-profile implant did not result in significant bone formation.

Purpose: The use of a magnesium-based bone cement, OsteoCrete, has shown promise as a means to secure bone and tendon-to-bone connections in orthopedic medicine. The presence of a bone cement to fill the residual socket and stabilize a dental implant during healing could make immediate implant placement in molar sites more predictable. The aim of this study was to determine whether this magnesium-based bone cement can be used predictably for this purpose. Materials and Methods: The mandibular third premolars and first molars were extracted bilaterally from four mongrel dogs (60 to 80 lb each). Implants were placed in each extraction socket and supported by only 2 to 3 mm of apical furcation bone. OsteoCrete bone cement was placed randomly for implant stabilization in half of the sites. Clinical healing was evaluated until the 4-month time point. All animals were then sacrificed, and mandibular en bloc resection was performed for histologic evaluation of the biologic response and bone-to-implant contact. Results: Clinically, healing showed a poor response when the test site implant was left exposed in a one-stage manner. No statistically significant difference was noted in bone-to-implant contact (52% in test sites versus 44% in control sites). Histologic specimens showed no adverse biologic response to the material but only minimal replacement at 4 months. Conclusions: OsteoCrete bone cement was successful in stabilizing the immediate dental implant in a large extraction socket when placed in a closed environment in the dog model but did not show a benefit as compared to controls. The limited data warrant further studies to determine the further potential of this material.

Purpose: Recently, it has been revealed that bone marrow-derived mesenchymal stem cells (MSCs) accelerate the healing of skin wounds. Although the proliferative capacity of MSCs decreases with age, MSCs secrete many growth factors. The present study examined the effect of mesenchymal stem cell-conditioned medium (MSC-CM) on wound healing. Materials and Methods: The wound-healing process was observed macroscopically and histologically using an excisional wound-splinting mouse model, and the expression level of hyaluronic acid related to the wound healing process was observed to evaluate the wound-healing effects of MSC, MSC-CM, and control (phosphate-buffered saline). Results: The MSC and MSC-CM treatments accelerated wound healing versus the control group. At 7 days after administration, epithelialization was accelerated, thick connective tissue had formed in the skin defect area, and the wound area was reduced in the MSC and MSC-CM groups versus the control group. At 14 days, infiltration of inflammatory cells was decreased versus 7 days, and the wounds were closed in the MSC and MSC-CM groups, while a portion of epithelium was observed in the control group. At 7 and 14 days, the MSC and MSC-CM groups expressed significantly higher levels of hyaluronic acid versus the control group (P .05). The expression level of hyaluronic acid was lower at 14 days than at 7 days in all three groups. Conclusions: Both the MSC and MSC-CM groups accelerated wound healing versus the control group to a similar degree. Accordingly, it is suggested that the MSC-CM contains growth factor derived from stem cells, is able to accelerate wound healing as well as stem cell transplantation, and may become a new therapeutic method for wound healing in the future.

Purpose: The zygomatic implant is mainly indicated for the rehabilitation of extremely atrophied maxillae when bone augmentation should be avoided. One drawback of zygomatic implants, which typically pass through the sinus, is initial or late bone resorption around the implant neck, which can result in oroantral communications followed by possible infection of the sinus. To decrease the risk of sinus infection, a modified technique was developed to preserve the integrity of the sinus membrane and to regenerate bone around zygomatic implants using an extended sinus grafting approach. Materials and Methods: Patients with extremely atrophied maxillae were provided with one to four zygomatic implants in conjunction with sinus grafting, plus conventional auxiliary implants, for immediate support of a provisional full-arch maxillary prosthesis. Definitive prostheses were delivered at 6 months after implant placement. All patients underwent clinical and radiographic examinations at 6 months. Results: Twenty-two zygomatic and 23 conventional auxiliary implants were placed in 10 patients. The overall 6-month implant survival rate was 90.9% for zygomatic implants and 100% for auxiliary implants placed in the anterior area. Only two minor technical complications were seen, and clinical indicators (including probing pocket depth, keratinized tissue, and plaque and bleeding indices) were good in all patients. A substantial gain of radiographic bone around the zygomatic implants was observed. Conclusion: The proposed technique led to successful prosthetic function for all patients. With the described technique, exposed implant threads within the maxillary antrum are eliminated and the potential for biologic complications is minimized.

Purpose: The objective of this study was to histologically evaluate and compare the effects of the permeability of shields on bone augmentation in a rabbit calvarial model. Materials and Methods: Twelve adult male Japanese white rabbits were used for the study. Each received four titanium cylinders, which were placed into perforated slits made in the outer cortical bone of the calvaria and filled with autologous iliac bone. The tops of the cylinders were randomly covered with the following test materials: (1) uncovered (control), (2) a titanium mesh, (3) an expanded polytetrafluoroethylene (e-PTFE) membrane, or (4) a titanium plate. After 8 weeks, the animals were sacrificed, and ground sections were obtained for histomorphometric analysis. Results: There was no significant difference in augmented bone volume among all groups. However, the distribution of augmented bone in the cylinders differed among the groups. In the uncovered control, there was significantly less augmented bone in the upper third of the cylinder than in the middle or lower thirds. Findings were similar for the titanium mesh group and the e-PTFE membrane group, with significantly less augmented bone in the upper third than in the middle or lower thirds. In the titanium plate group, there was no significant difference in augmented bone among the upper, middle, and lower thirds. The differences among the upper, middle, and lower thirds of the cylinder were smaller in the order of titanium plate, e-PTFE membrane, titanium mesh, and uncovered control. Conclusion: The use of low-permeability shields resulted in small differences in the distribution of bone structure in the present bone augmentation model.

Temporomandibular disorders (TMD) are a class of degenerative musculoskeletal conditions associated with morphologic and functional deformities that affect up to 25% of the population, but their etiology and progression are poorly understood and, as a result, treatment options are limited. In up to 70% of cases, TMD are accompanied by malpositioning of the temporomandibular joint (TMJ) disc, termed "internal derangement." Although the onset is not well characterized, correlations between internal derangement and osteoarthritic change have been identified. Because of the complex and unique nature of each TMD case, diagnosis requires patient-specific analysis accompanied by various diagnostic modalities. Likewise, treatment requires customized plans to address the specific characteristics of each patient's disease. In the mechanically demanding and biochemically active environment of the TMJ, therapeutic approaches that can restore joint functionality while responding to changes in the joint have become a necessity. One such approach, tissue engineering, which may be capable of integration and adaptation in the TMJ, carries significant potential for the development of repair and replacement tissues. The following review presents a synopsis of etiology, current treatment methods, and the future of tissue engineering for repairing and/or replacing diseased joint components, specifically the mandibular condyle and TMJ disc. An analysis of native tissue characterization to assist clinicians in identifying tissue engineering objectives and validation metrics for restoring healthy and functional structures of the TMJ is followed by a discussion of current trends in tissue engineering.

Four patients underwent posterior sandwich osteotomy combined with sinus floor grafting using bone morphogenetic protein-2 and other grafting materials. The patients were treated over a period of 4 years. Two to four implants were placed in each site subsequently. Of the 12 implants placed, none failed. Alveolar crest bone levels appeared to be stable over time, with an average vertical gain of about 5 mm. Overall vertical gain, including the sinus graft, exceeded 13 mm in all patients. The procedure appears to hold promise for combined vertical alveolar defects and prominent pneumatization of the posterior maxilla.

Oral soft tissue plays an important role in the structure and function of the oral cavity by protecting against exogenous substances, pathogens, and mechanical stresses. Repair of oral soft tissue defects that arise as a result of disease, trauma, or congenital abnormalities is often accomplished via transplantation or transfer of autologous mucosal tissue. However, this method of treatment can be complicated by the relatively small amount of autologous mucosal tissue that is available, as well as by the morbidity that may be associated with the donor site and patient reluctance to have oral (eg, palatal) surgery. To circumvent these problems, clinicians have turned to the fields of tissue engineering and regenerative medicine to develop acellular and cellular strategies for regenerating oral soft tissue. This review focuses on the efficacy and safety of cell-based investigational approaches to the regeneration of oral soft tissue.

Purpose: The present study tested a recently introduced bone substitute material (BSM) with a novel structure to determine its osteoinductive and osteoconductive properties in vitro and in vivo. The specific aims were to determine the microstructure of the as-manufactured BSM, as analyzed with scanning electron microscopy, and to characterize different cellular interactions. Materials and Methods: Human bone marrow stromal cells were cultured in the presence of the BSM. In vitro, attachment of osteoblastlike cells (SAOS-2) to the BSM was observed with the scanning electron microscope. The expression of genes related to osteogenic differentiation (alkaline phosphatase, bone sialoprotein, type I collagen, and osteocalcin) was determined by reverse-transcriptase polymerase chain reaction. In vivo, bone formation was examined with a murine model of ectopic bone formation through histology and computed tomographic scanning by using tissue-engineered constructs with the BSM and ovine bone marrow stromal cells. Results: Early cellular attachment could be detected as early as 6 hours. Cellular morphology developed in the following 66 hours toward a starlike appearance. Human bone marrow stromal cells cultured in the presence of the BSM showed no reduction in their viability. Osteocalcin was up-regulated during cell culturing, demonstrating an osteoinductive effect of BSM. Histologic and computed tomographic analyses showed the formation of new bone surrounding BSM particles, and a vascular meshwork was observed in the porosity of the particles. Conclusion: The analyzed bone substitute of synthetic origin presented osteoinductive properties that may exert a differentiative stimulus upon osteoprogenitor cells. The tested material allowed cellular adhesion of osteoblastlike cells and, following tissue construct implantation in vivo, supported the formation of new bone.

Purpose: To increase the understanding of the applicability of biomaterials and growth factors in enhancing stem cell-based bone regeneration modalities, this study evaluated the effects of enamel matrix derivative (EMD) and recombinant human transforming growth factor-beta (rhTGF-β) on osteoblastic differentiation of human bone marrow mesenchymal stem cells (hBMSCs) as well as human periodontal ligament stem cells (hPDLSCs). Materials and Methods: hBMSCs and hPDLSCs were obtained, and identification of stem cell surface markers was performed according to the criteria of the International Society for Cellular Therapy. Each group of stem cells was separately treated with a serial dilution of EMD (10, 50, and 100 μg/mL) or rhTGF-β (10 ng/mL). Osteoblastic differentiation was examined through in vitro matrix mineralization by alizarin red staining, and mRNA expression of osteopontin and osteonectin was determined by quantitative reverse-transcriptase polymerase chain reaction. hPDLSCs were further assessed for osteocalcin mRNA expression. Stem cells cultured in osteogenic medium were employed as a standard positive control group. Results: In none of the experimental groups were bone-related mRNAs detected subsequent to treatment with EMD for 5, 10, and 15 days. Alizarin red staining on day 21 was negative in EMD-treated BMSC and PDLSC cultures. In rhTGF-β-supplemented BMSC culture, expression of osteonectin mRNA was demonstrated on day 15, which was statistically comparable to the positive control group. Nevertheless, extracellular matrix mineralization was inhibited in both groups of stem cells. Conclusions: Within the limitations of this study, it could be concluded that EMD with a concentration of 10, 50, or 100 μg/mL has no appreciable effect on osteoblastic differentiation of BMSCs and PDLSCs. Application of rhTGF-β increased osteonectin mRNA expression in BMSCs. This finding corroborates the hypothesis that TGF-β might be involved in early osteoblastic maturation.

Two types of dentition are generated in a human's lifetime: the primary dentition, followed by the permanent dentition. Undoubtedly, teeth are essential for speech and mastication in both dentitions, but it is becoming apparent that dental pulp also plays a role in harboring mesenchymal stem cells (MSCs). To date, three kinds of MSCs derived from dental pulp have been established: permanent tooth, primary tooth, and immature apical papilla. The dental pulp from primary teeth is considered a particularly good source of MSCs; it can be obtained from extracted primary teeth, of which humans have 20. The past decade has seen many reports of dental pulp-derived MSCs, and the field is becoming increasingly popular. The present article describes the characterization of dental pulp-derived MSCs from primary teeth. It also discusses future banking activity of primary teeth, because it is known that dental pulp-derived MSCs have similar potential to those derived from bone marrow. Methods with which to optimize the cryopreservation process should therefore be investigated, because banked dental pulp may provide a great resource in future regenerative medicine.

The idea that somatic stem cells are localized in periodontal ligament (PDL) tissues as PDL stem cells (PDLSCs) responsible for construction and reconstruction of the periodontium has been widely accepted. Many dental scientists have attempted to clarify the identity of these PDLSCs, but the number of PDLSCs localized in PDL tissues is too small to be routinely and conveniently analyzed. Therefore, researchers have been attempting to develop undifferentiated PDL cell lines by transducing them with genes that are suitable for immortalization. The present authors were the first to succeed in establishing two clonal human PDL stem/progenitor cell lines that possessed multipotency derived from PDL tissues and that expressed PDL-related molecules as well as neural crest- and embryonic stem-related markers. The differentiation stages of these cell lines appeared to vary based on their potential to differentiate into other lineage cells, their response to tissue regeneration-related cytokines, and their behavior when transplanted into immunodeficient rats. This review describes the phenotypes of these cell lines compared with reported PDLSCs or other MSCs and discusses contemporary circumstances related to PDL regenerative medicine. Differential analyses between these two clones will reveal the mechanism of differentiation of PDLSCs as well as their phenotypes. The results will also allow for the acquisition of a mass population of PDLSCs or other stem cells directed toward PDL-lineage cells and to develop an unmet treatment needed for construction and reconstruction of PDL tissues based on tissue engineering techniques.

Periodontitis is a chronic inflammatory disease associated with loss of periodontal attachment, collagen, and alveolar bone. Regeneration of periodontal tissues can be supported by the local application of enamel matrix derivative (EMD). However, periodontal regeneration remains a major and often unpredictable challenge as the result of a number of unknown factors. The authors' in vitro studies revealed that EMD stimulated the wound fill rate, proliferation, and adhesion of periodontal ligament (PDL) cells. However, in the presence of an inflammatory environment or biomechanical loading, the beneficial effects of EMD decreased significantly. EMD also stimulated the synthesis of growth factors and collagen, as well as calcium deposition, in PDL cell cultures. These beneficial effects of EMD on PDL cells were also significantly diminished by inflammation and biomechanical forces, respectively. The findings suggest that critical PDL cell functions pertinent to periodontal regeneration are reduced in an inflammatory environment and under biomechanical loading. Therefore, effective anti-infectious and anti-inflammatory periodontal treatment before the application of EMD may be critical to ensure the full regenerative capacity of the PDL tissue. Furthermore, occlusal loading of EMD-treated teeth, at least immediately following surgery, should be minimized to obtain optimal regenerative healing results. A better understanding of the interactions of growth factors and biomechanical signals will result in more powerful regenerative therapeutic strategies.

Dental stem cells are excellent for oral and craniofacial tissue engineering. A profound knowledge about molecular processes in dental stem cells is necessary to create treatment approaches in oral medicine. Transcription factors regulate gene expression and provide decisive information for cellular functions. In recent years, the authors have investigated transcriptomes in dental stem cells before and after osteogenic differentiation. The present paper reports on the potential role of selected transcription factors, including ZBTB16, TP53, and SP1, in dental stem cell differentiation. This review discusses putative molecular processes in dental stem cells and summarizes the current knowledge.

Innovative developments in the multidisciplinary field of tissue engineering have yielded various implementation strategies and the possibility of functional tissue regeneration. Technologic advances in the combination of stem cells, biomaterials, and growth factors have created unique opportunities to fabricate tissues in vivo and in vitro. The therapeutic potential of human multipotent mesenchymal stem cells (MSCs), which are harvested from bone marrow and adipose tissue, has generated increasing interest in a wide variety of biomedical disciplines. These cells can differentiate into a variety of tissue types, including bone, cartilage, fat, and nerve tissue. Adipose-derived stem cells have some advantages compared with other sources of stem cells, most notably that a large number of cells can be easily and quickly isolated from adipose tissue. In current clinical therapy for periodontal tissue regeneration, several methods have been developed and applied either alone or in combination, such as enamel matrix proteins, guided tissue regeneration, autologous/allogeneic/xenogeneic bone grafts, and growth factors. However, there are various limitations and shortcomings for periodontal tissue regeneration using current methods. Recently, periodontal tissue regeneration using MSCs has been examined in some animal models. This method has potential in the regeneration of functional periodontal tissues because the various secreted growth factors from MSCs might not only promote the regeneration of periodontal tissue but also encourage neovascularization of the damaged tissues. Adipose-derived stem cells are especially effective for neovascularization compared with other MSC sources. In this review, the possibility and potential of adipose-derived stem cells for regenerative medicine are introduced. Of particular interest, periodontal tissue regeneration with adipose-derived stem cells is discussed.

Somatic stem cells have been acknowledged for their ability to differentiate into multiple cell types and their capacity for self-renewal. Some mesenchymal stem cells play a dominant role in the repair and reconstruction of periodontal tissues. Both dental-derived and some non-dental-derived mesenchymal stem cells possess the capacity for periodontal regeneration under certain conditions with induced differentiation, proliferation, cellular secretion, and their interactions. Stem cell-based tissue engineering technology promises to bring improvements to periodontal regeneration, biologic tooth repair, and bioengineered implants. The present review discusses the roles and values of various somatic stem cells in periodontal regeneration.

Purpose: Recent studies have shown that periodontal ligament stem cells (PDLSCs) play a key role in periodontal regeneration. However, the origin of these cells remains unclear. Meanwhile, bone marrow is thought to be the most common source of adult stem cells in many tissues and organs. Thus, the present investigation sought to determine whether systemically delivered bone marrow-derived mesenchymal stem cells (BM-MSCs) could participate in periodontal regeneration and differentiate into periodontal-specific cells and to explore the origin of PDLSCs. Methods: Enhanced green fluorescent protein (EGFP)-labeled BMMSCs were delivered into lethally irradiated rats by intra-bone marrow (IBM) transplantation. Four weeks after transplantation, periodontal defects with and without infection of anaerobic cultured Porphyromonas gingivalis were established. The animals were killed 1, 2, 4, or 6 weeks after periodontal defect surgery. Histomorphologic analysis, direct observation with the fluorescence microscope, and immunohistochemical staining were performed to evaluate the localization and differentiation of BM-MSCs. Results: EGFP-positive BM-MSCs could be observed as early as 1 week after surgery, and the number of EGFP-positive cells reached a maximum at 2 weeks. Meanwhile, EGFP-positive cells were observed in the newly formed bone, PDL, and cementum 4 weeks after surgery. Immunohistochemical staining verified that EGFP-positive BM-MSCs could differentiate into osteoblasts. Conclusions: These findings provide direct evidence that BM-MSCs can participate in and modulate periodontal regeneration.

Sinus floor grafting with bone morphogenetic protein-2 for transsinus implant placement or as a salvage technique for sinus-involved peri-implantitis has been found to be successful. Transsinus implants for All-on-Four treatment, zygomatic implants including quad zygomatics, and infected transsinus implants underwent peri-implant grafting, which was found to seal off the sinus cavity from the oral cavity in an effort to prevent or treat sinusitis/peri-implantitis.

This paper reports on the results of a structured review of the literature concerning in vivo molecular assessment of osseointegrated endosseous dental implants. A search of electronic databases was performed up to and including August 2011. Thirty articles met the inclusion criteria. A descriptive evaluation and analysis of the gene expression data concerning the process of osseointegration were performed. Broad consensus was observed among the study results, perhaps as a result of the similar targeted gene expression events. More recent investigations using gene arrays or gene profiling techniques offer new insights into the fundamental molecular events that support the osseointegration process. Evidence for the influence of surface topography on osteogenesis and osteoinduction has been reported. Additional investigations are required to further solidify the functional associations between individual or orchestrated gene expression events and the clinical result of osseointegration.

With the advent of nanotechnology, an opportunity exists for the engineering of new dental implant materials. Metallic dental implants have been successfully used for decades, but they have shortcomings related to osseointegration and mechanical properties that do not match those of bone. Absent the development of an entirely new class of materials, faster osseointegration of currently available dental implants can be accomplished by various surface modifications. To date, there is no consensus regarding the preferred method(s) of implant surface modification, and further development will be required before the ideal implant surface can be created, let alone become available for clinical use. Current approaches can generally be categorized into three areas: ceramic coatings, surface functionalization, and patterning on the micro- to nanoscale. The distinctions among these are imprecise, as some or all of these approaches can be combined to improve in vivo implant performance. These surface improvements have resulted in durable implants with a high percentage of success and long-term function. Nanotechnology has provided another set of opportunities for the manipulation of implant surfaces in its capacity to mimic the surface topography formed by extracellular matrix components of natural tissue. The possibilities introduced by nanotechnology now permit the tailoring of implant chemistry and structure with an unprecedented degree of control. For the first time, tools are available that can be used to manipulate the physicochemical environment and monitor key cellular events at the molecular level. These new tools and capabilities will result in faster bone formation, reduced healing time, and rapid recovery to function.

Purpose: Previous studies have demonstrated the capacity of a designed proline-rich synthetic peptide to stimulate osteoblast differentiation and biomineralization in vitro. Therefore, the aim of the present study was to evaluate the osseointegration capacity of titanium (Ti) implants coated with these peptides in a rabbit model. Materials and Methods: Four calibrated defects were prepared in the tibiae of three New Zealand rabbits, and the defects were randomized into a test group (peptide-modified machined Ti implant) and a control group (unmodified machined Ti implant). The performance in vivo was investigated after 4 weeks of implantation by real-time reverse transcriptase polymerase chain reaction of bone and inflammatory markers, microcomputed tomographic analysis of mineralized bone, and histologic examination. Results: The peptides adsorbed in agglomerates on Ti and underwent a change in secondary structure upon adsorption, which induced an increase in surface wettability. Gene expression markers indicated that peptide-coated Ti implants had significantly decreased mRNA levels of tartrate-resistant acid phosphatase. A trend toward increased osteocalcin in the peri-implant bone tissue was also seen. Bone morphometric and histologic parameters did not show significant differences, although the peptide group showed a higher percentage of new bone histologically. Conclusions: Proline-rich peptides have potential as a biocompatible coating for promoting osseointegration of Ti implants by reducing bone resorption.

Purpose: This study describes the use of an innovative dynamic implant valve approach (DIVA) for dental implant placement and sinus augmentation procedures. Materials and Methods: The DIVA implant system was tested in vitro for leakage and mechanical fatigue. A closed sinus elevation procedure with a gel-type bone substitute was performed using the DIVA implant in a swine model (n = 6). Implants were placed and evaluated radiographically and histologically. Results: Elevation of the maxillary sinus membrane and augmentation were performed in a simple, minimally invasive fashion. Histologic analyses demonstrated complete sealing of the DIVA implant and excellent osseointegration. Conclusion: The DIVA can be used as a simplified viable option for dental implantation and augmentation procedures. Hermetic sealing of this implant system, which features an inner screw, renders it safe.